This commit introduces the `output::cell::DisplayWidth` struct, which
encapsulates the Unicode *display width* of a string in a struct that makes it
less easily confused with the *length* of a string.
The use of this type means that it's now harder to accidentally use a string's
length-in-bytes as its width. I've fixed at least one case in the code where
this was being done!
The only casualty is that it introduces a dependency on the output module from
the file module, which will be removed next commit.
A recent change to ansi-term [1] means that `ANSIString`s can now hold either
owned *or* borrowed data (Rust calls this the Cow type). This means that we
can delay formatting ANSIStrings into ANSI-control-code-formatted strings
until it's absolutely necessary. The process for doing this was:
1. Replace the `Cell` type with a `TextCell` type that holds a vector of
`ANSIString` values instead of a formatted string. It still does the
width tracking.
2. Rework the details module's `render` functions to emit values of this
type.
3. Similarly, rework the functions that produce cells containing filenames
to use a `File` value's `name` field, which is an owned `String` that
can now be re-used.
4. Update the printing, formatting, and width-calculating code in the
details and grid-details views to produce a table by adding vectors
together instead of adding strings together, delaying the formatting as
long as it can.
This results in fewer allocations (as fewer `String` values are produced), and
makes the API tidier (as fewer `String` values are being passed around without
having their contents specified).
This also paves the way to Windows support, or at least support for
non-ANSI terminals: by delaying the time until strings are formatted,
it'll now be easier to change *how* they are formatted.
Casualties include:
- Bump to ansi_term v0.7.1, which impls `PartialEq` and `Debug` on
`ANSIString`.
- The grid_details and lines views now need to take a vector of files, rather
than a borrowed slice, so the filename cells produced now own the filename
strings that get taken from files.
- Fixed the signature of `File#link_target` to specify that the
file produced refers to the same directory, rather than some phantom
directory with the same lifetime as the file. (This was wrong from the
start, but it broke nothing until now)
References:
[1]: ansi-term@f6a6579ba8174de1cae64d181ec04af32ba2a4f0
src/feature/xattr.rs:6:5: 6:22 warning: unused import, #[warn(unused_imports)] on by default
src/feature/xattr.rs:6 use std::ffi::CString;
^~~~~~~~~~~~~~~~~
The buggy code assumed that, if output isn't to a terminal, then the only view available is the Lines view. This is incorrect, as the Details view doesn't require a set width either, so check for --long even when there's no set width.
One of those two date formats was re-compiled before any date was displayed. Now they are compiled only the first time they're used, and cached versions are used thereafter, resulting in a speedup.
Instead of using the getopts crate’s dynamically-generated usage string, use a more static one:
- The options are organised by category now
- You can use `--help --long` to display only the ones that pertain to `--long`
- They’re aligned in a table sort of way
It could be generated statically, because all the options to change it are determined at compile time, but they’re not, yet...
Technically speaking, picking which timestamp to show for a file is a function of an output module, rather than the file itself. This also means that the `output::column` and `file` modules are now completely separate.
By taking the file names as a mutable vector, we can avoid having to allocate a new one when it’s empty. The recent changes to Options::getopts have made it more obvious that we could move the same vector out of getopts’s matches, instead of cloning it there.
This cleans up the options module, moving the structs that were *only* in use for the columns view out of it.
The new OptionSet trait is used to add the ‘deduce’ methods that used to be present on the values.
Changes to the way ANSIStrings work mean we need to dereference the strings before putting them in an ANSIString. There's more that can be done here, but this gets it to compile for now.
